Phonograph



u 1945 J. J. ANTALEK 2,382,461

PHGNOGRAPH Filed March 9, 1942 M5 AMPLIFIER nsrecnm J: A0010 AMPLIFIER ENTOR Jim Jami/2 MWM Patented Aug. 14, 1945 PHONOGRAPH John J. Antalek, Chicago, Ill., assignor to Virgil Hamilton, doing business as Hamilton Associated Industries, Chicago, Ill.

Application March 9, 1942, Serial No. 433,876

14 Claims.

It is an object of my invention to provide improved circuits for the reproduction of sound from phonograph records or the like.

A further object of the invention is to provide phonograph record pick-up amplifying circuits having a higher signal to noise ratio, and an improved frequency response to the higher audio frequencies.

A further object of the invention is to provide improved reproducing and amplifying circuits for a phonograph or radio phonograph, which shall obtain greater fidelity and qualit in the reproduction of frequencies within the audio range.

A more specific object of the invention is to provide improved pick-up and reproducing circuits for phonograph record players, whereby the record player may be more effectively associated with a radio receiver or a public address system.

A further important object of the invention is to provide phonographic pick-up and reproducing circuits wherein the pick-up circuit effects modulation of high or radio frequency oscillations by absorption of energy from the high or radio frequency oscillations, in accordance with the frequency or amplitude of the signals in the pick-up circuit.

Other andfurther objects and advantages of this invention will be apparent from the following description when taken in connection with the accompanying drawing, wherein- Figure l is a schematic diagram of a portion of a radio receiver or amplifier associated with an energy absorbing phonographic pick-up circuit, accordin to the present invention;

Figure 2 is a schematic diagram of a modified form of phonographic reproducing circuit embodying features of the present invention;

Figure 3 is a schematic diagram oi another form of a phonographic reproducing circuit embodying the features of the present invention;

Figure 4 is a schematic diagram of a modified energy absorption circuit which may replace the energy absorption circuit shown in Figure 3; and

Figures 5 and- 6 are schematic diagrams representing other forms of pick-up circuits which may be employed with reproducing circuits of Figures 1, 2, and 3.

In the circuit shown in Figure 1, the thermionic vacuum tube 2 may be the mixer tube of a radio receiver. This tube may comprise a plate I, a

screen grid 6, a controd grid 8, an oscillator an- (c1. 179-1oo.11)\

ode In, an oscillator grid 12, and a cathode H. The control grid 8 is connected by the wire l6 to the usual radio signal input circuits l8. The wire I 6 may be shorted to ground by switch 28 during the use of the receiver for phonographic reproduction purposes. The oscillator grid I2 is connected by a wire 22 t a resistor 24 grounded by wire 26. An oscillator tank circuit comprising the coil 28 and adjustable condenser 88 in parallel is connected across the resistor by a wire 32, and a wire 34 in which is interposed a condenser 36. The oscillator anode I0 is connected to screen grid 8, and both are connected by the wire 38 to the positive screen grid supply voltage terminal 48.

The output or plate circuit of the tube 2 is cou- I pied to the input of an amplifier tube 42 by means of a doubly tuned transformer-amplifier coupling 44, comprising a primary winding 46 interposed in the lead 48 from the plate I to the positive direct current plate supply terminal 58.. The primary winding 46 is tuned by the condenser 52. The secondary winding-54, having a greater numberof turns than the primary winding, is connected on the one side b the wire 58 to the control grid 58 of the amplifier tube 42, and on the other side by the wire to the usual automatic volume control tap, the secondary winding being tuned by the condenser 82. The cathode 84 of the tube 42 may be grounded by the usual selfbiasing resistor 68 shunted by condenser 88. The screen grid is connected in the usual manner by the wire 10 to the positive voltage supply terminal l2, and the plate 14 is connected in the usual manner to the output circuits 18, which may, for example, include a diode detector, audio amplifier and speaker common in radio receivers.

The phonographic pick-up circuit "is inductiveiy related to the doubly tuned transformeramplifier coupling 44. This circuit may, for example, comprise a coil positioned in inductive relation with the secondary winding 54 and/or the primary winding 46. A capacityDick-np 82 having a record traversing stylus 8 is connected in parallel to the coil 80 as by e'wires 88 and 88. A resistor 90 is preferably connected as by the wires 92 and 94 in parallel with both the coil 80 and the capacity pick-up or condenser 82. The capacity pick-up 82 may be generally of the construction disclosed in the application of Frank B. Tatro, Serial No. 387,792, filed April 10, 1941, or of other suitable known construction.

The'oscillator tank circuit comprising coil 28 and condenser 30 is tuned to the same frequency as the coupling 44-, while the phonographic pickup circuit 13 is designed to be resonant at, or to be tuned to, a frequency within the band-pass frequency range, or width of the coupling 44, that is, to a frequency within plus or minus eight kilocycles of the frequency to which the coupling 44 is tuned. The coupling 44 may be designed for tuning to an intermediate frequency, or it may be designed for tuning to a radio frequency. Similarly, too, amplifier tube 42 and its associated circuits may be designed for amplifying intermediate frequency signal currents, or it may be designed for amplifying radio frequency signal currents.

The pick-up circuit 13 absorbs high or radio frequency energy from the amplifier coupling 44, and this absorption of energy is varied in amplitude, in accordance with the variation in Impedance of the pick-up 32, thereby to effect an amplitude modulation of the carrier, or unmodulated signal supplied to the coupling from the oscillator section of the mixer tube. The amplitude modulated intermediate or radio frequency is then amplified by the tube 42, and then by the usual circuits of the radio receiver following this tube, converted into audio signals, amplifled and fed to the loud speaker.

In a tuned radio frequency receiver, tube 2 may be an oscillator, as distinguished from a mixer tube, and coupling 44 may comprise a radio frequency transformer, and the tube 42 may be a radio frequency amplifier tube. In a superheterodyne receiver the oscillator section of a mixer tube circuit may be used to supply the carrier or unmodulated signal at an intermediate frequency, or a, separate oscillator may be used to feed a carrier or unmodulated signal into the mixer tube. Harmonic frequencies of the oscillator or oscillator section may be employed in both the tuned radio frequency receiver and the superheterodyne receiver. Thus, the transformer coupling 44 may be tuned to a harmonic of the carrier or unmodulated signal supplied by the oscillator or oscillator section.

It is preferred to tune the pick-up circuit to a frequency within the band-pass width of the amplifier coupling 44 but not to the exact frequency to which this coupling is tuned, as previously stated. However, for certain types of receivers or phonographs, it may be desirable to tune the pick-up circuit to the exact frequency of the amplifier-coupling 44. This will cause an increase in the high frequency signal voltage applied to the input of the diode or detector regardless of whether the capacity change of the pickup 32 is plus or minus. In a receiver or reproplus and minus changes in the impedance of the pick-up, are to be avoided, the pick-up circuit may, therefore, be tuned to the exact frequency of the amplifier-coupling 44.

point of the coil I00, while the plate I02 is con-- nected through resistor I2: to the positive plate supply voltage terminal I24 and by wire I23 through blocking condenser I Ilto suitable output circuits I33 of usual construction converting radio frequency signal voltages into audio frequency signal voltages, and applying the same to a phone or loud speaker.

A pick-up circuit I32 may comprise a coil I34 inductively related to the coil I03, the capacity pick-up I36 shunting the coil I34, and a resistor I33 shunting both the coil I34 and the pick-up I33. The lower end of the coil I34 and the common connections to the resistor and pick-up are grounded as at I40. The tank circuit I08-IIO should be tunded to a frequency within the band width of the tuned circuit I34--I36. As the impedance of the pick-up I36 is varied by the phonograph record, a combined frequency and amplitude modulated signal is produced in the output of the tube I00. Either of these modulation characteristics may be employed, as desired, by the use of appropriate, known output circuits I30. Thus, the circuit I30 may be of the type for transmitting frequency modulated signals or merely the type transmitting amplitude modulated signals.

In the case of a superheterodyne reproducing circuit or receiver, the tube I00 may be a separate oscillator feeding into the radio frequency or intermediate frequency amplifier, or the electrodes of tube I00 with the associated oscillator circuit may constitute the oscillator section of the mixer tube of the superheterodyne circuit. In the case of a tuned radio frequency reproducing circuit or receiver, the tube I00 may constitue an oscillator tuned to a signal frequency within the band width of the tuned radio frequency circuit or receiver.

In the circuit shown in Figure 3, an oscillator detector tube I42 may comprise a plate electrode I 44, a control grid I43, and a cathode I48. The pick-up and oscillator tank circuit are here combined, the oscillator coil I50 being shunted by the capacity pick-up I52. The cathode is connected to an intermediate point of the coil I50 by the wire I54 and the control grid is connected to the oscillator circuit by wire I56, wire I53 in which is interposed the grid condenser I60, and the wire I62 in which is interposed the grid resistor or leak I34. The plate I44 is grounded as at I33 through the by-pass condenser I33, and

' the plate end of the oscillator circuit is grounded as at I10. The plate is also connected throughthe resistor I12 to the positive direct current plate supply terminal I14, and through blocking condenser I13 to an audio output circuit I13 of any suitable known construction, comprising an audio amplifier and speaker or phone fed by the amplifier.

A tuned energy absorption circuit I30 may comprise a coil I32 adjustably connected inductively to the coil I60. The coil I32 is shunted by a condenser I84, and both are shunted by a resistor I36. The circuit I30 is tuned to within plus and minus six to eight kilocycles of the oscillator frequency. Variations in impedance of the pick-up I62, in accordance with the lateral undulations of the record groove, effect frequency modulation of the oscillator along the steep linear portion of the selectivity curve of the tuned absorption circuit I30, resulting in the varying of the amount of power dissipated in this absorption circuit. Because of this energy or power loss. the voltage across the oscillator tank coil I30 will also vary in accordance with the amplitude of the recording. Since this tank coil I30 is connected acrossa grid and cathode of the oscillator detector tube I42, these amplitude variations inv radio frequency signal voltage are detected therein and supplied to the output circuit as audio frequency currents or voltages. This reproducing circuit of Figure 3 is, therefore, especially adapted to feed audio amplifiers, and, accordingly, is of particular advantage for use in public address systems,

A modified absorption circuit I88 is shown in Figure 4, and this circuit may be substituted for the absorption circuit I80 of Figure 3. The absorption circuit I88 comprises a variable coupling coil I in series with a resistor I92 and a condenser I 84, the connected ends of the coil and condenser being grounded as at I80. The circuit I88, like the circuit I80, is tuned within plus and minus six to eight kilocycles of the oscillator frequency.

Figure 5 illustrates a pick-up circuit I98 which may be substituted for the pick-up circuit I0 in Figure 1, or for the pick-up circuit I32 in Figure 2. The pick-up circuit I98 may comprise a coil 200 for inductive coupling with the doubly tuned transformer-coupling 44 of Figure 1 or the coil I08 of Figure 2. One end of the coil is grounded as at 202 and connected to a resistor type pick-up 204, which may be of any conventional structure. The condenser 206 for tuning the pick-up circuit, in accordance with the requirements of the circuit of Figure 1 or the circuit of Figure 2, is connected in series with coil 200 and'the resistor pick-up 204. Figure 6 illustrates a pick-up circuit 208, which may be substituted for the pickup circuit 18 of Figure 1 or the pick-up circuit I32 of Figure 2. This pick-up circuit 208 comprises an inductance pick-up 2I0, which may be inductively related to the doubly .tuned coupling M of Figure 1 or the coil I08 of Figure 2, or it may be arranged in series with another inductance coil so coupled. The inductance provided by the pick-up M0 or the pick-up in series with another inductance is tuned by a. condenser 2I2 and both shunted by resistor 2. The condenser 2I2 tunes the pick-up circuit 208 in accordance with the requirements of the circuit of Figure 1 or the circuit of Figure 2.

It is thought that the invention and numerous of its attendant advantages will be understood from foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention or sacrificing any of its attendant advantages, the forms herein described being preferred embodiments for the purpose of illustrating the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a phonograph reproducer, a reproducing circuit comprising means including a tuned circuit for supplying an unmodulated high frequency wave, an absorption circuit coupled to said tuned circuit for absorbing energy from said tuned circuit and including an energy absorbing and dissipating resistance, and a phonograph pick-up in one of said circuits for varying the amount of energy absorbed by said absorption circuit to effect amplitude modulation of said supplied high frequency wave.

2. In a phonograph reproducer, a reproducing circuit comprising a sound reproducer, means including a tunable circuit for supplying an unmodulated high frequency signal, means for modulating said high frequency signal, and means independent of said modulating means for transmitting the modulated signal to the sound reproducer, said modulating means comprising a tunable absorption circuit coupled to said first tunable circuit forabsorbing energy from'said first tunable circuit and including an energy absorbing and dissipating resistance, and a phonographic pick-up, one of said circuits including and being tuned by said pick-up for varying the amount of energy absorbed by said absorption circuit to eiTect amplitude modulation of said supplied signal.

3. In a phonograph reproducer, a radio reproducing circuit including a mixer tube having an oscillator section, oscillation determining circuits connected to said oscillating section of the tube for producing high frequency oscillations, an amplifier, a tuned circuit coupling the output of said mixer tube to the input of said amplifier, and an energy absorption circuit coupled to said, tuned circuit, said energy absorption circuit including an energy absorbing and dissipating resistance and an impedance varying pick-up for varying the amount of energy absorbed by said absorption circuit to effect an amplitude modulation of the oscillations supplied to said amplifier through said coupling.

' 4. In aphonograph reproducer, a reproducing circuit comprising an amplifier, means including a tuned circuit for supplying unmodulated high frequency signals to said amplifier, an energy absorption circuit inductively coupled to said tuned circuit and including an energy absorbing and dissipating resistance, an impedance varying phonographic pick-up forming part of said energy absorption circuit for varying the amount of energy absorbed by said absorption circuit to effect the amplitude modulation of the signal supplied to said amplifier.

5. In a phonograph reproducer, a reproducing circuit including an amplifier,means including a tuned circuit for supplying unmodulated radio frequency oscillations to said amplifier,'an energy absorption circuit having inductive and capacitive branches tuning said absorption circuit to a frequency within the band width of the tuned circuit and including an energy absorbing and dissipating resistance, and a phonographic pickup included in one branch of said energy absorption circuit for varying the amount of energy absorbed by said absorption circuit to effect amplitude modulation of the signal supplied to said amplifier.

6. In a phonograph reproducer, a reproducing circuit comprising an amplifier, means including a double tuned transformer coupling for supplying unmodulated high frequency oscillations to said amplifier, an impedance varying phonographic pick-up, and an energy absorption circuit including .said phonographic pick-up and other impedance tuning said absorption circuit to a frequency within the band width of said coupling, one of said impedances being inductively coupled to said double tuned transformer coupling whereby variations in the impedance of said pick-up vary the energy absorbed by said absorption circuit to eflect amplitude modulation of the oscillations supplied to said amplifier.

7. In a-radio phonograph, a radio receiver having a mixer tube section, a high frequency amplifier, and a tuned coupling between the mixer tube section and the amplifiena phonographic circuit comprising a variable impedance phonographic pick-up, and another impedance tuning said phonographic circuit to a frequencywithin the band width of the tuned coupling circuit, one of said impedances being inductively coupled to said tuned coupling circuit whereby variation in impedance of said pick-up varies the energy absorbed by said phonographic circuit from said tuned coupling circuit to effect amplitude modulation of the signals fed from the mixer tube to an amplifier.

8. In a phonograph reproducer, a reproducing circuit comprising an oscillator having a tank circuit, an energy absorption circuit having an impedance coupled to said tank circuit and including an energy absorbing and dissipating resistance, and a phonographic pick-up forming part of said energy absorption circuit for varying the amount of energy absorbed by said absorption circuit to effect modulation of the oscillations of said oscillator.

9. In a phonograph reproducer, a reproducing circuit including a high frequency oscillator having a frequency determining tank circuit, an energy absorption circuit comprising an energy absorbing and dissipating resistance, an impedance varying phonographic pick-up for varying the amount of energy absorbed by said absorption circuit to effect modulation of the oscillations supplied by said high frequency oscillator, and another impedance tuning said absorption circuit, one of said impedances being inductively coupled to said tank circuit, said tank circuit being tuned to a frequency within the frequency band width of the absorption circuit.

10. In a phonograph reproducer, a reproducing circuit comprising an oscillator having an oscillation determining tank circuit, a capacity varying record pick-up, and an energy absorption circuit coupled to said oscillator and comprising said pick-up, an inductance coil shunting said pick-up for tuning said energy absorption circuit and a resistance for dissipating the energy from said circuit, said pick-up on variation of said capacity varying the amount of energy delivered to said resistance for dissipation thereby to effect modulation of the oscillations supplied by said oscillator, said tank circuit being tuned to a frequency within the band width of the energy absorption circuit.

11. In a phonograph reproducer, a reproducing circuit comprising an oscillator, a tank circuit, an impedance varying phonographic pick-up, said tank circuit having inductance and capacitive branches, of which one branch includes said pick-up, said oscillator having a signal output circuit, and a tunable energy absorption including an energy absorbing and dissipating resistance, said absorption circuit being coupled to said tank circuit and tuned to a frequency approximating the oscillator frequency for producing audio signals in the output circuit of said oscil- -ance coupling said grid to said cathode and to said plate, a capacity varying record pick-up in shunt to said inductance and tuning said inductance, a plate-to-cathode audio signal output circuit, and an energy absorption circuit inductively coupled to said inductance and comprising inductance and capacity tuned to a frequency approximating the frequency to which the inductance coupling the grid to the plate and cathode inductance is tuned by said pick-up, whereby the frequency modulated oscillations produced by said pick-up effect amplitude variations in signal between the grid and cathode, thereby producing signals of audio frequency in the signal output circuit of said tube.

13. In a phonograph reproducer, a reproducing circuit comprising a thermionic tube having plate, cathode and grid electrodes, an inductance coil coupling said grid to said cathode and to said plate, a capacity varying record pick-up shunting said coil, a plate-to-cathode audio signal output circuit, and an energy absorption circuit comprising a second inductance coil inductively coupled to said first coil, a resistance and a condenser in series with said second coil, said absorption circuit being tuned to a frequency within the side bands of the oscillations in the circuit of said first inductance and said pick-up.

14. In a phonograph reproducer, a reproducing circuit comprising an oscillator, an amplifier, a tuned coupling between said oscillator and amplifier for supplying unmodulated high frequency oscillations to the input of said amplifier, and an energy absorption circuit, said energy absorption ciruit including an energy absorbing and dissipating resistance, an inductance inductively coupled to said tuned coupling, and a capacity varying phonographic pick-up in shunt to said inductance for varying the amount of energy absorbed by said absorption circuit to effect modulation of the unmodulated oscillations supplied through said coupling to the input of said amplifier;

JOHN J. ANTALEK 

